linux-kernel - Re: [PATCH] iwlwifi: dvm: fix NULL pointer dereference in rxon

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Message-ID: <5d06a246c7a38668423da3d0fc43db5ee38d08a2.camel@sipsolutions.net>
Date: Wed, 04 Feb 2026 13:25:16 +0100
From: Johannes Berg <johannes@...solutions.net>
To: dhyaan19022009-hue <dhyan19022009@...il.com>, kvalo@...nel.org
Cc: linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iwlwifi: dvm: fix NULL pointer dereference in rxon

On Wed, 2026-02-04 at 17:31 +0530, dhyaan19022009-hue wrote:
> From: Dhyan K Prajapati <dhyan19022009@...il.com>
> 
> When bringing up the wireless interface via virtual monitor mode,
> iwlagn_bss_info_changed() can be called with a NULL bss_conf pointer
> during ieee80211_add_virtual_monitor() -> ieee80211_do_open() sequence.
> 
> This causes a NULL pointer dereference when the function attempts to
> access bss_conf fields at offset +0x10.
> 
> Crash signature:
>   BUG: kernel NULL pointer dereference, address: 0000000000000000
>   RIP: 0010:iwlagn_bss_info_changed+0x19d/0x640 [iwldvm]
>   Call Trace:
>    drv_link_info_changed+0x2b5/0x2c0 [mac80211]
>    ieee80211_link_info_change_notify+0x13d/0x160 [mac80211]
>    ieee80211_recalc_txpower+0x5c/0x60 [mac80211]
>    ieee80211_assign_link_chanctx+0x182/0x410 [mac80211]
>    ieee80211_add_virtual_monitor+0x17c/0x2b0 [mac80211]
>    ieee80211_do_open+0x6d8/0x740 [mac80211]
> 
> Add an early NULL check for bss_conf before accessing its members.

If that really can happen, that'd be a mac80211 bug, not to be fixed in
a random driver. I see the crash above, but you've not even described it
correctly, it seems more likely to me that iwl_rxon_ctx_from_vif()
returned NULL.

johannes